Need to replace big old galvanized pipe with pex

lucidsoul5

Hi, I own a 1300 sq ft 2 story farm house from 1929 with an unfinished basement.  I want to finish the basement but some of the boiler pipes are hanging low and are huge.  I can tell the old owner had a gravity boiler at one time and did not want to pay to replace the pipe running to each of the radiators, so they left the huge 2 & 3 in galvanized pipe running under the first floor on the basement ceiling.  These are the pipes hanging low that I want to replace.  The old owner also replaced the huge cast iron radiators with baseboard radiators that are 1/2 inch copper.  Also the galvanized running to the second floor is 3/4 inch so I do not want to replace this and avoid opening my walls. My boiler is a gas burning 10 year old using 1 1/4 inch copper pipe.  My question now is, can I replace the large galvanized pipe with 1 inch pex barrier?  So I would have 1 1/4 boiler pipe attached to 1 inch pex to all of the 1/2 copper radiators on the first floor.  The same 1 inch pex would attach to the 3/4 galvanized running upstairs which are attached to the same 1/2 copper baseboard radiators. 

JStar

Pipe

Here's the one answer that everybody hates hearing...It depends.



It depends on the heat loss of each room, and the ratings of the heat emitters. With those numbers, you'll need to calculate the required flow to each run. And then, after that, you'll be able to determine pipe size.

JStar

Piping

Point being...if you guess, you'll likely guess wrong. Proper calculations and design prevent a lot of wasted time/money/energy.

lucidsoul5

Still a Novice

Thanks for the quick reply.  I am still learning when it comes to this boiler system so its nice to check my ideas with pros that know more than me.  When using barrier Pex, are there two different flavors?  One for baseboard heating and one for radiant heat?  I saw to different kinds on one site but the description looked identical.  Alsod do I need to wrap the pex  to insulate and avoid heat loss on the runs? 

Snowmelt

Sizing

You have to size the pipe to the flow, you have to figure your flow with heat load of room by delta tee x 500.



I'm going to say it again John Barba has a good webinar on this. Taco hvac . Com.



Then you have to do a pressure drop with pex, copper or black pipe.



All pex manufacture have there pressure drop documented on there websites.

Rich_49

9 zones

there is nothing ridiculous about 9 zones . Every room should be very comfortable zoned in such a manner . Why heat a room that doesn't need heat ?  Find out the highest head loss zone Bc and try to use a Taco Bumble Bee . With rads and a low head loss running at 30* Delta T odds are that you may be able to run below the 42 watt max for that circulator . I don't remember exactly but are you gonna be using that AO for DHW and Space heating ?

Zman

Pex

I agree with jstar, you have to do the math.

How is the piping being run? Is this a reverse return system?

Take your time and do this right. There are far too many folks using rules of thumb and guessing.

Carl

lucidsoul5

Just replacing a few pipes

I understand the need for calculating and planning for a new boiler or repiping an entire system but I just want to replace a few oversized galvanized pipe with 1 inch pex. My delta t is 20 and I have 1 zone in a 1300 sq home. My boiler has 1 1/4 pipe, I want to connect 1 in pex to that and run it to the 1/2 copper baseboards on the first floor. The second floor has 3/4 runs connected to 1/2 baseboards, which it will not replace, just connect the 1 in pex to it in the basement before it runs up and on the return. Does this sound logical?

JStar

Pipes

It doesn't sound logical. You are just guessing at the 1" being the correct size. That is illogical.

icesailor

1" PEX:

IMO, the Engineer has it right.

If you have a 1,800 sq. ft. house with baseboard, and 1 1/4 supply and return at the boiler, and cast iron baseboards (because some are 3/4" and some are 1/2"), you probably have a "monoflow" system and it splits to 1", going back to the 1 1/4". If you do, put two zone valves at the 1" split and make the building two zones. I don't understand all this galvanized pipe. No one used that stuff for heat. Are you sure that the pipe isn't painted silver?

What you are trying to do is hellacious expensive and difficult. If you got three prices from people that gave the price on what you want to do, and only one gave you choices of alternates, that price would be so much lower that you would think the other two were pirates and acting like the Florida dentists I've been to.

Some of us can think of far better ways to spend your money effectively and not doing what you are contemplating.

Its no longer an amazing fact to me about what people learn to live with once they find out how much it cost to do it. Some of us have spent a lot of valuable learning time, figuring out how to do these type of things and what it will cost. We end up chalking it up to "learning experiences". Or, at least that's what I had to chalk it up to. Uncompensated time.

icesailor

2" & 3" pipes in basement:

Your pipes may measure 3" and 2" in the basement OUTSIDE diameter, but are probably 2" and 1 1/2" INSIDE diameters.

Even in 1929, it took bigger mens with strong backs to thread 3" pipe. It cost more money too. The boiler may have had 3" connections but those old dead Mens used t' reduce to 2" or less for their circuits as fast as they could. If you've ever tried to thread 2" pipe without a Power Drive, you understand.  A geared threader threading 3" pipe was really tiring. You REALLY want a power drive and a universal for that.

lucidsoul5

Two zones

Icesailor,



Sorry for the confusion, all my baseboards are 1/2 copper.  The original owner replaced the big old rads with copper 1/2 baseboards but didn't want to spend the money replacing the iron pipe (I have been calling it galvanized because that's what it looked like to me).  The 2nd floor has 3/4 in iron pipe runs and the 1st floor has 3 in, 2 in and a few 1 in iron pipe.  All of this leads to the boiler which is much newer and is 1 1/4 copper.  Someone mentioned that the pipe is smaller diameter on the inside and they are correct, I removed a small run in the kitchen last year which had the 2 in iron pipe and it was smaller on the inside.  That said, I really like your idea of creating a second zone for the 2nd floor.  We constantly over heat the upstairs when trying to heat the taller ceiling downstairs.  I didn't think replacing the iron pipe (100 ft) would be that expensive, around $500 with pex and fittings.  No?

lucidsoul5

Help

BC3510



     Your house is similar to mine and I am getting scared by the others telling me "DONT GUESS or ELSE".  Am I crazy for choosing 1 in pex to replace similar iron pipe?  Should I just match the iron pipe with copper, which will be expensive?  Seems silly to do that right?  The iron pipe is oversized on the outside and smaller diameter on the inside.  So lets say I am replacing 2 in and 1 1/2 iron pipe with 1 inch pex.  Shouldn't that be enough?  To recap: 1 1/4 copper in and out of the boiler, 1 in pex to all of the six 1/2 copper baseboards on the first floor.  Same 1 in pex to the 3/4 runs to the 2nd floor which attach to the seven 1/2 copper baseboards.  All of the baseboards are 1/2 copper. 

Rich_49

Lucid

What type of boiler and make and model of circulator if you would please .  Also 1 eighteen hundred sq ft house may very well be absolutely different than another .  One may have more windows , one may have 2 x 4 walls as opposed to 2 x 6 walls , one may have undergone a deep energy retrofit  or received newer upgrades at some point . Point being  that a room by room heat load calculation should be performed . Anyone that tells you different is a fool and listen to him at your own peril . You say there used to be radiators and they were changed to 1/2 baseboard , is this baseboard run as a series loop or does each piece of radiation have it's own takeoff from the main ?  You could very well listen to someone and end up with a 60* Delta T and returning water to a non condensing boiler at 120* or less . Another possibility is that your circulator may be sized properly for the system as it is now and if you change without knowing the head losses and flow rates in the real world you may end up with little to no heat when you really need it .  Problem with internet advice is you cannot verify whom everyone is and their credentials .  Mine and others on here are verifiable and we have been solving problems for quite some time .  If 40 people tell you something that is the endorsed first step of any heating work and another says don't worry about it you may want to try what the consensus advises and take every precaution to do it right . 

  As stated before by another many of us have spent many uncompensated hours correcting things that we did that did not work , we also call this tuition . I hope you will take our advice and not just undertake this without the proper information first . 

  You would be right to question any advice you got from anyone on here but many of us have been here solving difficult to not so difficult problems for quite awhile and some of us will proudly show their work , This is who I am ,

http://mechanical-hub.com/langans    This house has Ng bills that are heading toward the projected 1,140.00 per year while having temps when the heat is on that do not differ more than one degree from room to room  and consumes less electric than many small 3 zone houses . Please heed what many have said to you here .,

Rich_49

This is why

that room by room heat loss calc is so important .

lucidsoul5

You were right``

I had a hvac guy come out tonight and quote the job so I could ask some questions.  He said exactly what you did.  The water flow has no problem flowing through the smaller 1/2 and 3/4 pipe so I should not worry about the 1 in pex.  I am going to take your 2nd zone advice while I am making the changes.  Thx again and Ill let you know how it turns out. 

JStar

Pipe

We're neglecting half of the concern here. Yes, the 1" pipe might satisfy RESTRICTION and FLOW, but will it handle the required VOLUME?



It's not about fear...it's a healthy concern for implementing proper calculations learned from experience and study.

icesailor

Understanding:

Well, just barely.



As we Plumbers understand it, "Pipes increase as do their squares". Therefore, it takes 4 -1/2" pipes to equal a 1" pipe, and 4 - 1" pipes to equal a 4" pipe. However, the 4 - 1/2" pipes have more internal surface area to create friction. Therefore, the 1" pipe is better than 4 - 1/2" pipe because of less friction.

A 1/2" ID X 10" length of copper tube holds .102 gallons of water

A 3/4" X 10'ength of copper holds .216 gallons of water. The total is .318 Gallons'

A 1" X 10' length of copper holds .408 gallons or something along that.

Rich_49

wire, zone valves and controllers OH MY

I must be much less sophisticated than you . I would have fitted bypass fittings and TRVs , set it up constant circulation and been done with it .  Still a good system that you have there though  

JStar

Pipe

You might be able to install 3/4" pipe. That's my point here. You can waste a lot of time and materials and money by guessing.

icesailor

Picky,picky:

If we're going to be picky,picky, and go at it from a perfect engineering point of view, 1" PEX ID is considerably less than I" Type L or M Copper tube.

1" PEX ID (Inside Diameter) is .882".

1" Type L Copper ID is .995" and Type M is 1.025". Therefore, 1" Type M copper tube can carry more hot water for a longer distance than 1" PEX.

The PEX has the same Outside Diameter as the copper tube. Just a much thicker wall thickness.

So, to compare 1" PEX to CTS or Iron Pipe size needs further calculations.

So when IBR or some other source give you a maximum length with new/smooth nominal size pipe, they don't give a minimum, just a maximum. With 1" PEX being in between the capacity of 1" CTS and 3/4" CTS, you have to do some serious calculations to be correct.

1" PEX is not a straight line substitute for 1" CTS or nominal pipe or tube.

Because Pipes increase as do their squares, how much can 1/2" CTS PEX carry compared to 1/2" Type M copper tube?  No one will tell me. I had to figure it out myself and it isn't pretty.

Zman

No idea...

I still have no idea how you existing system is piped and honestly cannot make a suggestion.

It sounds like you have a gravity system that has been converted and has had some baseboards added. How did they pipe it?

If you are changing the main distribution piping , the way it is piped is far more important than the size of the pipe.

If you post a piping drawing, you will get better advise.

Otherwise, more guessing....

Carl

Rich_49

Lead installer

is also designer . For the record .

  Am I to understand your theory to state that decreasing the main header piping from 1 1/2 Iron pipe to 1" pex will not increase the mechanical energy required for the circuit significantly ?  Is it also not likely that the flow will change from what seems to be laminar to turbulent thus increasing the thermal transfer before even reaching the emitters ?

Several have asked questions that would assist us in offering proper advice but the OP has yet to answer anything of importance or benefit . He seems to be quite happy engaging your theory in this endeavor so maybe you could make it private as opposed to provocative .

Lucid , in case you did not know . Most of the problems we encounter and help people work through here are caused by HVAC Guys .   By the way you might as well use 3/4 copper because the I.D of 1" pex is just about the same .

  If you want some real valuable advice give us some information like the length of the 2 & 3" pipes you speak of , the number of emitters and their lengths and locations where they connect to these large diameter pipes . There is more to this than you are being led to believe and many factors that MUST be given the proper consideration . I have seen systems that had mains designed and installed by HVAC guys that did not work , I have also seen a disturbing amount of stuff drawn and sealed on plans that would have failed miserably .  There is probably a reason that short - fat headers are preferred now by most .  

Rich_49

Precise engineering

 We have seen many instances where someone was off a little bit on a number of things and had systems where nothing worked . Precise is exactly what is needed , without precise you don't know that you'll do no harm . 

  We know nothing of this guys system except for some very vague information .

 This house could have a requirement 39K if it is leaky and in one climate zone , in another climate zone it might require 54K . The radiation that is 1/2 baseboard could be greatly oversized and placed in the header in a location that would not allow other emitters the required thermal energy to perform . We don't even know how many BTU the home is , where it is , what size is the boiler , lengths of supply and return devices , is the 3/4 even 3/4 anymore , how many feet of 1/2 baseboard there is on each circuit . To offer any advice before possessing this information could certainly do harm .  That is what is mostly done here , properly assisting people , not doing no harm . 

  What an accomplishment it would be to leave people in no worse a position than they were in when they came here as opposed to actually sending them away with a precise resolution to their problem .  I'm sure that's what our host had in mind when he started this .

Rich_49

System

works utilizing a 2" & 3" OD header delivering the medium to the emitters . Will it continue to do so with less volume , will it have velocity noise and can we deliver the GPM through the smaller ID piping ?  It is a good possibility it won't perform the same .

lucidsoul5

I will get a drawing and measurements

I really appreciate everyone trying to help, so the afternoon I will map the system with measurements. Aside from that I know my delta t is 20. Is there any other info I can provide to help besides a map of the system?

Rich_49

Baseboard

include how many feet for each piece and what circ you have .  Make and model of boiler also

icesailor

Post Photo's

Post photo's if you can. The way you draw it might not be the actual way it is installed. A common problem.

Charlie from wmass

Non Faulty logic doing a heat loss

will let us know what temperature the heating fluid needs to be to meet design temperatures. Heating the room is a relative term. Savings can be had if the owner is lucky enough to find the room can be heated with say 150 degree F water as opposed to the 180 degrees it has been running.

RobG

One other

One other reason to do the math is that one inch PEX does have a smaller ID but the fittings have an even smaller ID! Don't go on with your project on a wing and a prayer. Better to do the footwork beforehand and KNOW that you are right. There are many assumptions being thrown out here, but assumptions are like opinions which are like ********'s. Everybodys got one. Do it once, do it right.



Rob 

lucidsoul5

Pics

Okay, this took some doing. The diagram is all my basement pipes attached to the rads on the first floor. There are four sets of 3/4 pipe stubs representing the pipe going to the 2nd floor. Each set of 2nd floor pipe has a 3/4 run attached to a 1/2 copper 10 foot baseboard. Boiler pic is hard to read sorry. The pipes are 2 in, 1 1/2, 1 in, 3/4, all attached to 1/2 copper baseboards.

lucidsoul5

More detail

M

Rich_49

Can you

scan both of these drawings and then attach the pictures in PDF . They are small and cannot be viewed well when I increase the size

lucidsoul5

Ok

I will resubmit today

lucidsoul5

It took me a few months working on the weekends but I did it. I replaced all of the galvanized pipe with copper, instead of pex. I decided to use copper because i know how to solder and i was already in unfamiliar waters so I went with what i knew. I used 1-1/4 coming out of the boiler and 1in , 3/4 and 1/2 going to each baseboard. I finally purged most of the air and have good heat going to each run. During my installation i divided the runs into upstairs and downstairs in order to install 2 zones once if felt confident that I could get the heat back on. So I have a few questions: do I have to put the zone valve on the return side or the supply side, or it doesn't matter. Also, can someone suggest equipment, TACO valves? do I need a controller too? I am creating 2 zones both using 3/4 pipe. Does each thermostat attach to each zone valve or is that what I need a zone controller for. Any suggestions on how to's or books to read would be appreciated. If the wiring is semi easy I can figure it out. Thx in advance.

lucidsoul5

Thx for the shopping help. I just ordered 2 zone valves and the controller. I am hoping for easy installation so stand by for a barrage of newbie questions.

lucidsoul5

Hey, they took out the comments from my friend that helped me. Are you still out there "BC????"

lucidsoul5

Well I know there are others here that can help so I bought a TACO 3 Zone Controller and 2 Honeywell Zone Valves to install a 2 zone system in my house. Could someone explain exactly what to do with the 2 yellow and 2 red lines from each zone valve.

lucidsoul5

Sorry the models are TACO Zone valve Zvc403-4 and two honeywell zone valves v8043 E